1. Field of the Invention
The present invention relates to a communication terminal apparatus provided with a Session Initiation Protocol (hereafter, abbreviated as “SIP”) adapter device which establishes a session based on SIP in cooperation with an SIP server to enable facsimile communication by way of an Internet protocol (hereafter, abbreviated as “IP”) network, and also relates to a facsimile communication method.
2. Description of the Related Art
There are known related art documents disclosing techniques relating to an adapter device for use in a communication terminal apparatus. For example, Japanese Laid-Open Patent Publication No. 2004-32288 (Document 1) proposes a communication adapter device for use in an IP telephone set. This communication adapter device enables a user to connect his/her IP telephone set to destination communication equipment, while selecting either via an Internet network or via a conventional subscriber network through a predetermined operation on the IP telephone set. The communication adapter device is also able to allow the user as a caller to confirm a type of the currently used network after establishing connection to the destination communication equipment. For this purpose, the communication adapter device has network selection means for selecting a network to be used for communication with other destination communication equipment based on information indicating a telephone number input through external communication equipment, and communication control means connected to the destination communication equipment based on the telephone number via the selected network to control the communication. The communication adapter device further has coder-decoder (hereafter, abbreviated as “CODEC”) means for converting an analog voice signal to a digital signal or converting a digital input signal to an analog signal.
Japanese Laid-Open Patent Publication No. H7-245692 (Document 2) proposes a communication adapter device for use in a facsimile terminal, which is suitable for connection between a frame-relay network and a plurality of facsimile terminals. The communication adapter device has an RAM (random access memory) which stores an accommodated terminal information table for storing management information for managing accommodated terminals, and a destination identification table for storing information of a destination terminal connected via a frame-relay network.
Japanese Laid-Open Patent Publication No. H8-167936 (Document 3) proposes a mobile phone which is designed to have two different telephone numbers so that these telephone numbers are switchably used for respective different purposes, and with restrictions on conversation with the switched telephone number. The mobile phone has means for registering the two telephone numbers in association with various data including available areas where sending and receiving calls with the respective two telephone numbers are permitted, times and dates of use, and destination telephone numbers, and means for determining, when a call is sent or received with a selected telephone number, whether or not the data conditions are satisfied in correspondence with the telephone number.
There have been proposed facsimile devices having network functions (hereafter, referred to as the “network facsimile devices”), and these network facsimile devices employ a transmission/reception method as described below. When performing facsimile transmission/reception on a network, a mail address of a receiving network facsimile device is input on a transmitting network facsimile device, and data is transmitted to a mail server by using an Internet FAX (facsimile) service. The receiving network facsimile device then receives the data from the mail server with Post Office Protocol (hereafter, abbreviated as “POP”) 3 or Internet Message Access Protocol (hereafter, abbreviated as “IMAP”). As is well known, both POP 3 and IMAP are protocols for receiving electronic mails from a server storing the electronic mails on Internet or intranet.
In addition to the transmission/reception method described above, there has been proposed a method to enable transmission and reception with Direct Simple Mail Transfer Protocol (hereafter, abbreviated as “direct SMTP”) by inputting an IP address or a host name of a receiving network facsimile device on a transmitting network facsimile device. The direct SMTP is a communication method in which a receiving network facsimile device has a SMTP server function so that transmission and reception with SMTP are possible without involving a mail server.
However, the transmission/reception method and communication method as described above which use identification codes (for example, mail addresses, IP addresses, or host names) in addition to publicly well known telephone numbers, require storage or management of these identification codes. This causes users to feel troublesomeness and inconvenience.
It is therefore desired to make it possible to access an SIP server or the like present on a network and to perform conversion between a telephone number and an IP address so that an image can be transmitted to a desired destination only by inputting the telephone number. Additionally, it is desired to enable a network facsimile device, namely a network image communication function and an analog facsimile communication function to fully exhibit these functions.